The present invention is directed to an improved apparatus for processing of gears and for removing irregularities on gear tooth surfaces. The present invention is an improvement of the basic gear burnishing apparatus of U.S. Pat. No. 3,321,820 which issued May 30, 1967 to Guenter K. Rosendahl and which is assigned to the assignee of the present invention. The method and apparatus of the prior Rosendahl Patent utilized three burnishing gears which operated on a work gear to remove irregularities on gear tooth surfaces.
In general use are electronic gear checking or gear inspecting machines which determine gear accuracy by meshing and rolling a gear with a master gear of established accuracy. Deviation from the master gear pattern are noted and recorded for such factors as tooth spacing errors and involute inaccuracies which become apparent variations between centers of the gear being tested and the master gear. A portion of the errors are due to small nicks and to minor bumps caused by heat treatment scale, chips, scratches, burrs and foreign particles including dust particles which cling to the teeth surfaces. Such particles may produce test readings of sufficient magnitude to effect a subsequent rejection of the gear during testing even though there are no errors basic to gear accuracy and suitability.
The method and apparatus of the Rosendahl Patent utilized three burnishing gears all of which had substantially equal operating pressure angles and which rolled in mesh with the work gear to reduce irregularities on the gear tooth surfaces of the work gear. While the invention of the Rosendahl Patent provided an appreciable improvement in the processing of gears, the tips of the gear teeth were still subject to nicks and burrs and all areas of the gear tooth flank were not uniformly burnished. Both of these factors have not been found due to the fact that all three burnishing gears of the Rosendahl apparatus employed substantially equal operating pressure angles. The present invention, by utilizing three burnishing gears, all of which have different operating pressure angles, overcomes the above-described problem that was present in the Rosendahl apparatus.